Gable top cartons are formed from a single sheet of paperboard material that is folded to define an upstanding side wall enclosure, a sealed bottom and an initially sealed top that is capable of being periodically opened and closed to access the material stored in the carton. The paperboard sheet or blank, from which the gable top carton is formed typically is coated or laminated on both sides with a plastic and/or may also include foil on one side to prevent the material stored in the carton from leaking and to prevent liquids from wicking into the paperboard material of the carton.
The side wall enclosure of the typical prior art gable top carton comprises a total of four rectangular side walls consecutively articulated to one another and disposed in opposed parallel pairs. One rectangular side wall is securely adhered by heat sealing to a side seam panel that is hingedly connected to an adjacent rectangular side wall panel. The bottom of the prior art gable top carton is defined by an array of bottom panels that are folded into overlapping relationship to one another and that are securely and substantially permanently sealed. The top of the prior art gable top carton includes a pair of rectangular roof panels that converge toward one another. Arrays of hingedly connected triangular panels extend between and connect the rectangular roof panels. Top seal panels are articulated to the rectangular roof panels and to the arrays of triangular panels. The top seal panels are secured in face to face relationship to seal the top of the prior art gable top carton.
The prior art gable top carton is opened by folding corner regions of the rectangular roof panels backwardly to more conveniently access one of the arrays of triangular panels extending therebetween. This first step of the carton opening generally can be carried out easily. The top seal panels of the triangular panels are then separated from the top seal panels of the rectangular roof panels, such that the triangular panels can be folded outwardly to define a pour spout. This second step of the prior art carton opening has presented difficulties as explained further below. The top of the prior art gable top carton can be reclosed by merely folding the triangular panels back inwardly such that the top seal panels again can be disposed in generally face to face relationship with one another. Re-openings and re-closings can be carried out as needed for further access to the materials stored in the carton.
The top opening region of the gable top carton has presented many design challenges to the container industry. In particular, all seams on the gable carton must be sufficiently secured to prevent leakage of material from the carton and to prevent spoilage or contamination of material stored in the carton. Heat sealing technology is sufficiently advanced to achieve a secure seal. In particular, the seals generally are achieved by applying heat and pressure to activate the heat seal coating for securely sealing the carton. However, in addition to being securely sealed, the pour spout of the gable carton top must also be easily openable. The functional differences between a permanently closed pour spout of a gable top carton and an easily openable pour spout are appreciated by all consumers who have inadvertently attempted to open the wrong side of a gable top carton or who have purchased one of the gable top carton where the easy opening feature was inadequate.
To facilitate the initial opening of the pour spout on the prior art gable top carton, selected regions of the top seal flaps typically are coated with an abhesive. The abhesive functions to at least partly minimize the effect of subsequently heat sealed flaps. Thus, regions of the pour spout on the prior art gable top are securely closed, but are intended to be openable with relative ease. A prior art gable top closure employing a water based abhesive is shown for example, in U.S. Pat. No. 4,775,096 which issued to Andersson et al on Oct. 4, 1988. Another prior art gable top carton that attempts to avoid abhesives by employing a specific combination of paperboard coatings and adhesive is shown in U.S. Pat. No. 4,903,891. The use of abhesive is considered undesirable in that it requires a separate precise coating step as part of the manufacturing process. An imprecise application of abhesive may affect the ability of the carton top to function as intended.
Despite the continued use of various abhesive, adhesive and paperboard coating combinations, there is a desire to provide a gable top carton having a pour spout that can be securely sealed, but which is predictably easily openable. One attempt to provide an easy opening pour spout with less reliance on complex combinations of abhesives, adhesives and coatings is shown in U.S. Pat. No. 4,828,539 which issued to Jonsson et al on May 9, 1989. U.S. Pat. No. 4,828,539 shows an array of very small diamond-shaped embossments being placed on regions of the various registered top seal panels that must be separated during opening to define the pour spout. This pattern of small raised surfaces is intended to achieve only limited regions of paperboard material to contact with the heating and pressure means for sealing the carton. The pattern of small embossments or raised surfaces taught by U.S. Pat. No. 4,828,539 still results in large contact areas for the sealing means, and hence does not adequately facilitate the initial carton opening. Furthermore, small embossments of one top seal panel must nest between embossments of an adjacent top seal panel to increase the contact area.
In view of the above, it is an object of the subject invention to provide a gable top carton having an easy opening pour spout.
It is another object of the subject invention to provide a gable top carton with a closure that does not rely exclusively upon combinations of abhesive and adhesive for facilitating the initial carton opening.
An additional object of the subject invention is to provide a gable top carton with efficient sealing and with predictable easy opening in the region of the pour spout.